Dowel bar assemblies are used at both expansion and contraction type joints in concrete slabs. The function of both types of joints is to control random cracking of the concrete slab. The concrete slabs vary in thickness, width and length but are typically designed for commercial, industrial and roadway uses. The function of the dowel bar assembly at the joint locations is to position the dowel at the mid-point of the slab or at half the thickness of the slab off of the grade. The dowel itself is used to control the misalignment of adjacent slab areas in both vertical and horizontal directions. As the slabs move in fractional amounts due to temperature and other dynamic forces, the dowels maintain the position of the concrete slabs.
Present dowel bar assemblies are manufactured using a fusion process or welding method to make fixed connections between wire frame components and between the wire frame and the dowel. The assembly process varies widely and ranges from very manual methods to highly automated methods of assembly. In all cases, the connection between the wire support frame and the dowel is a welded connection. This is typically also the case when utilizing tie bars instead of dowel bars.
Tie bar assemblies are very similar in design to dowel bar assemblies but are used at joints that will not allow movement. Tie bar assemblies are manufactured in the same way as dowel bar assemblies, however, the tie bar has a deformed surface rather than the smooth surface of a dowel bar.
In cases where corrosion protection is used on the dowels, the welding process damages the protective coating due to the high temperatures at the weld location. Additionally, manual and automatic welding processes lead to weld impurities which in turn lead to broken welds and displaced dowels. Additionally, due to the rigid nature of the welded connection, vibrations during transporting of the assemblies can result in broken welds. In addition to traditional dowel, certain dowels are made of fiberglass while others are hollow synthetic tubes that are filled with materials such as cementious grout. These types of dowels do not allow for their use in a welding application.
The typical welding process for manufacturing dowel bar assemblies exposes labor forces to unhealthy working conditions. Automatic production methods can alleviate the exposure to such conditions, however, large amounts of smoke are generated due to the high temperatures of the welding process. With the burning of protective coatings used on the dowel bar assemblies during the welding process, the exposure to unhealthy conditions is only magnified.
It is an object of the invention to provide a mechanical connection for a dowel bar assembly or tie bar assembly.
It is a further object of the invention to provide a mechanical connection for a dowel bar assembly or tie bar assembly which reduces exposure to harmful chemicals.
It is yet another object of the invention to provide a mechanical connection for a tie bar or dowel bar assembly, of various substances.